Electric snap switch with fluid-actuated toggle mechanism

ABSTRACT

A pressure-controlled snap switch in which the free end of a contact spring projecting between two spaced switch contacts is pivotable with a toggle motion from one contact against the other when a diaphragm in the switch housing is moved by the pressure of a liquid or gas. The movement of the diaphragm is transmitted to an adjustable control lever and the resulting swing of this lever is transmitted by a resilient link to a pivotable control spring whose free end is connected by a snap spring to the contact spring. The resilient link, whose opposite ends are connected to fixed points of the control lever and the control spring, may consist of a rod of rubber or plastic, or of an angular leaf spring or a torsion coil spring.

United States Patent Karl Roll Leinielden-Oberaichen, Germany; Carl A.H. M. Waskowsky, Oberglatt,

(72] lnventors [54] ELECTRIC SNAP SWITCH WITH FLUID- ACTUATED TOGGLEMECHANISM 13 Claims, 6 Drawing Figs.

[52] U.S. Cl 200/83 R, 200/67 D [51] Int. Cl ..I-I01h 35/34 [50] Fieldof Search 200/83,

DIG. l, DIG. 2, 67 D; 337/347 Primary ExaminerRobert K. SchaeferAssistant Examiner-M. Ginsburg AttorneyKarl F. Ross ABSTRACT: Apressure-controlled snap switch in which the free end of a contactspring projecting between two spaced switch contacts is pivotable with atoggle motion from one contact against the other when a diaphragm in theswitch housing is moved by the pressure of a liquid or gas. The movementof the diaphragm is transmitted to an adjustable control lever and theresulting swing of this lever is transmitted by a resilient link to apivotable control spring whose free end is connected by a snap spring tothe contact spring. The resilient link, whose opposite ends areconnected to fixed points of the control lever and the control spring,may consist of a rod of rubber or plastic, or of an angular leaf springor a torsion coil spring.

ELECTRIC SNAP SWITCH WITH FLUlD-ACTUA'IED TOGGLE MECHANISM The presentinvention relates to an electric pressure-controlled snap-action switchwhich is especially suitable for being employed in connection with alaundry or dishwashing machine or the like and is provided with at leastone mobile contact spring which projects between and is adapted toengage one or the other of a pair of normally fixed contacts and theoperation of which may be controlled by the movements of an element suchas a diaphragm which, when subjected to the pressure of a liquid or gas,acts upon a control lever which is loaded by an adjusting spring andacts upon a control spring or tongue which is operatively interposedbetween the control lever and the contact spring and is connected to thelatter by a toggle or snap spring.

The conventional snap switches of the type above described are providedwith a rigid tappet which is secured to the control lever and whose tipengages the control spring which is associated with the contact springand, when the control lever swings, also efi'ects a pivoting movement ofthe snap spring.

Since in the operation of the switch the control lever as well as thecontrol and contact springs carry out pivoting movements about theirrespective axes, these pivoting movements result in reductions in theeffective length of the control spring. Since the free end of thecontrol spring is pivotably connected to the snap spring which, in turn,is pivotably connected to the contact spring, these reductions in theeffective length of the control spring have a disadvantageous effectupon the snap spring and through the latter also upon the mobile contactspring.

According to the present invention it has now been discovered that thisdisadvantage of the known snap switches of the type described may beeliminated by connecting the control lever and the control spring ortongue to each other by means of a resilient elongate link instead ofproviding the control lever with a rigid tappet whose free end or tipmerely bears upon the control spring.

This resilient link forms a universal joint between the control leverand the control spring which permits both ends of this element to followindependently of each other the pivoting movements of the control leverand the control spring.

In order to insulate the control lever and the control springelectrically from each other, it is one feature of the present inventionto make this connecting element of an electrically insulating material,e.g. rubber or a suitable plastic. This connecting element may, forexample, consist of a pin or rod, a leaf spring or a torsion coilspring. By making this element of a suitable resilience different fromthe resilience of the control spring, the connecting element may alsoserve for temporarily storing the pressure or tension which is exertedby the control lever through this element upon the control spring. Whenthe control spring is about to snap through its dead center position tothe other side, the resilient connecting element will release thisstored force and thereby accelerate the snap action. Owing to thisstoring action of the connecting element, the control spring willtherefore also be pivoted from one to the other side and with a snapaction through its dead center position even though the diaphragm willbe acted upon only by a slow variation in pressure and will thereforepivot the control lever very slowly. The contacts on the contact springwhich is swung by the control spring and the interposed toggle or snapspring will therefore always rapidly make or break with the fixedcontacts.

According to one preferred embodiment of the invention, the resilientconnecting element is in the form of a solid rod of elastomericmaterial, i.e. rubber or a suitable plastic, whose opposite ends aresecured to the control lever and the control spring by being insertedinto bores of a smaller diameter in this lever and spring and by beingprovided near these ends with annular grooves into which the edges ofthe bores engage.

If the resilient connecting element is in the form of a leaf spring,this spring is preferably bent at such an angle that its effectivelength is determined by only one arm of this spring, while the other armextends substantially in the direction of movement of the control leverand thus practically does not affect the spring action of this leafspring. The upwardly bent arm may be provided with an aperture in whicha stop member may engage so as to limit the extent of the movement ofthe leaf spring relative to the control lever.

In addition, the leaf spring is preferably provided with a longitudinalslot through which the free end of the tappet may extend which projectsfrom the diaphragm plate and acts upon the control lever. If this leafspring is made of metal rather than of an insulating material, it isadvisable to insulate it electrically from the switch housing byproviding an insulating member between this spring and the controlspring and/or the control lever.

One of the fixed" contacts, which is operatively associated with thecontact spring and preferably forms the contact which the mobile contactspring engages when the diaphragm of the switch is not under pressure,is adjustable to different distances from the other fixed contact bybeing mounted on the free end of a spring whose other end is secured tothe switch housing and to a connecting terminal lead which projects fromthe housing. This spring presses against a setscrew by which it isadjustable relative to the other fixed contact. For this purpose, thisspring is preferably resilient only adjacent to the area where it issecured to the switch housing, while the other part of this spring isreinforced by ribs, stifiening corrugations or the like so as to berelatively nonresilient.

In order to prevent the spring carrying the adjustable contact fromexerting a pressure upon the switch housing which might possibly damagethe latter, the elasticity constant of this spring is preferably made assmall as possible by making this spring of a considerably thinnermaterial than the terminal lead thereof.

These and additional features and advantages of the present inventionwill become further apparent from the following detailed descriptionthereof which is to be read with reference to the accompanying drawingin which: I

FIG. 1 shows a cross section of a switch according to a first embodimentof the invention in its off position;

FIG. 2 shows a cross section of the switch according to FIG. I in its onposition;

FIG. 3 shows a cross section of a switch according to a secondembodiment of the invention in its off position;

FIG. 4 shows a view of a part of the leaf spring as seen from the leftthereof in FIG. 3;

FIG. 5 shows a modification of a ing to FIG. 3; and

FIG. 6 shows a cross section of a switch according to a third embodimentof the invention in its off position.

The snap switch according to the invention as illustrated in FIGS. 1 and2 comprises a diaphragm l which may be lifted by the pressure of aliquid or gas entering a chamber in the lower part of the switch housing10 through a hose nipple 2 or the like so that a central tappet 4 on aplate 3 which is connected to the upper side of the diaphragm 1 willthen act upon a control lever 6 which is pivotably mounted at one endabout a fulcrum 5. The other end 7 of this lever 6 acts upon the lowerend of an adjusting spring 8 whose upper end engages and is adapted tobe adjusted by a setscrew II which is screwed into a tubular extension 9of the switch housing 10.

Control lever 6 is further operatively associated with a mobile contactspring 13 one end of which is rigidly secured to a part of the housing10 by a rivet 12 while its free end 15 carrying a contact 14 projectsbetween a fixed contact 16 and an adjustable contact 17. Contact spring13 consists of a strong leaf spring which may bend resiliently onlyadjacent to its lefthand end which is clamped in a fixed position by therivet 12. This contact spring 13 is operatively associated with acontrol spring or tongue 18 one end of which is likewise clamped by therivet l2 and which is able to pivot from one to the other part of theswitch accordside of contact spring 13 through a longitudinal slot whichis provided in the contact spring 13. This control spring 18 isoperatively associated with a barrel-shaped snap or toggle spring 19 oneend of which acts upon the free end 20 of control spring 18 while itsother end is supported by and acts upon the inner edge 21 of the end ofthe slot in contact spring 13 through which springs 18 and 19 arepivotable.

As may further be seen in FIGS. 1 and 2, control lever 6 is bent so asto be pivotable outside of the area within which contact spring 13 andcontrol spring 18 are pivotable.

Control lever 6 and control spring 18 are directly connected to eachother by a rubber rod 22 whose opposite ends 23 and 24 project throughbores 25 and 26 in control lever 6 and control spring 18, respectively.For firmly securing the rubber rod 22 to lever 6 and spring 18, rod 22is provided near its opposite ends with annular grooves 27 and 28 intowhich the edges of the bores 25 and 26 tightly engage. This rubber rod22 forms an almost ideal resilient link between the control lever 6 andthe control spring 18 which permits the ends 23 and 24 of rod 22 tofollow the swing of the control lever 6 and also of the control spring18 without danger that the variations in the effective length of rod 22caused by the difierent pivoting movements will have any noticeableeffect. This rubber rod 22 also serves as an accumulator which storesthe pressure transmitted thereto from the diaphragm I through thecontrol lever 6, and which transmits this stored pressure to the controlspring 18 shortly before the latter is pivoted beyond its dead centerposition. This rubber rod 22 has the further purpose of serving as anelectric insulator between the control spring 18 and the control lever6. i

The adjustable contact 17 is secured to one end of a leaf spring 30which is bent twice at an angle and whose other end is electricallyconnected to a terminal lead 29 which projects from the switch housing10. Leaf spring 30 and terminal lead 29 are connected to each other andsecured to the housing by a rivet 31. For adjusting the position of thecontact 17, the end 32 of leaf spring 30 carrying this contact on itsside engages the end of a setscrew 33 which is screwed into a tubularpart 34 of the switch housing 10. Leaf spring 30 is further providedwith a stiffening corrugation 35 which insures that spring 30 will bendresiliently only next to its left-hand end I face 36 of thebottom part37 of the switch housing. When diaphragm l is in this inactive position,the control lever 6, the control spring 18 and the contact spring 13 arelikewise in their respective inactive positions in which the adjustingspring 8' presses the control lever 6 against a fixed stop 39 at theinside of housing 10 and the snap spring 19 bearing upon the free end ofthe control springl8 presses the contact spring l3 upwardly so that itscontact 14 presses against the adjustable contact 17.

FIG. 2 shows the same switch in its on position in which the diaphragm lis lifted by the pressure acting upon its lower side and the controllever 6 is thereby pivoted against the action of the adjusting spring 8toward the control spring 18. Owing to this pivoting movement, thecontrol lever 6 exerts through the rubber rod 22 a forceupon the controlspring 18 so that this spring has the tendency to pivot against theaction of snap spring 19 through its dead center position to the otherside. This pivoting movement of control spring 18 through its deadcenter position issupported by the pressure which, as previouslydescribed, is stored in the rubber rod 22. After the control spring 18has passed its dead center position, snap spring 19 presses the contactspring I3 suddenly into its on position as shown in FIG. 2 in which thecontact 14 engages the contact 16.

When the pressure upon the lower side of diaphragm I decreases, thediaphragm will again move downwardly and the control lever 6 will alsopivot back to its inactive position as shown in FIG. 1. This also causesthe control spring 18 to be retracted with the result that the contactspring 13 will again snap over to the other side. Since the returnmovement of control lever 6 also results in an extension of the rubberrod 22 in its longitudinal direction, a tension will be stored in thisrod with the result that, when control spring 18 snaps over to its otherside, this movement will be accelerated by the release of the tension ofrod 22.

FIG. 3 illustrates a modification of the switch according to theinvention likewise on the off position, the same as the switchaccording'to FIG. I. The corresponding parts of the the same referencenumerals. In place of the rubberrod 22 according to FIGS. 1 and 2, theswitch according to FIG. 3 is provided with an angularly bent leafspring 40. The free end 41 of the horizontal arm 42 of this spring 40 issecured by a rivet 43 to a tab 44 which is partly stamped upwardly outof the control lever 6 and extends parallel to the general plane of thatlever. The other arm 45 of spring 40 which is bent upwardly from the arm42 extends, however, substantially paral-' lel to the direction in whichthe control lever 6 is pivotable and its free end 46 serves forsupporting the end of the control spring 18 which engages the snapspring 19.

As illustrated particularly in FIG. 4, leaf spring 40 is provided with alongitudinal slot 47 which increases the elasticity of this springandhas a sufficient width to permit the upper end 48 of the tappet 4 on thediaphragm plate 3 to project freely therethrough. The free end of thearm 46 of leaf spring 40 is bifurcate in the manner shown in FIG. 4 soas to form two prongs 49 which reach around and over the sides of spring18 and together with the edge of a central boss 50 of spring 40 form adouble knife edge bearing for the control spring 18 on opposite faces ofthe latter.

Since in this embodiment of the invention the metallic leaf spring 40forms an electric connection between the control spring 18 and thecontrol lever 6, the fixed stop member-39 which limits the extent of thestroke of the control lever 6 consists of an electrically insulatingmaterial such as, for example, a plastic. The effect of the switch whichis equipped with such a leaf spring 40 is identical with that of theswitch according to FIGS. 1 and 2 which is provided with a rubber rod22.

FIG. 5 illustrates a modification of the leaf spring 40 as lastdescribed. Instead of being provided with the longitudinal slot 47, thisleaf spring according to FIG. 5 is provided withtwo apertures 51 and 52.While the aperture 51 in the horizontal arm 42 is large enough to permitthe upper end 48 of the tappet 4 to move freely therethrough, theaperture 52 in the other arm 45 of the leaf spring receives the bentoverend 53 of a stop member 54 projecting from the control lever 6. The end53 of stop member 54 has such a clearance in the aperture 52 that thearm 45 of leaf spring 40 and thus also the entire spring can move for adistance h relative to the control lever 6. The stop projection 53therefore limits the extent of the stroke h of leaf spring 40 relativeto the control lever 6 which has the advantage that the force which isstored in and by the leaf spring 40 will become effective only in theimmediate vicinity of the dead center position of the control spring 18.By limiting the stroke h of leaf spring 40 so as to make it effectiveonly within the particular area in which it is'of practical value, thefurther advantage is attained that the storage of force by ad in thisspring requires only a relatively small amount of energy which, in turn,requires only small variations in pressure upon the diaphragm 1, eventhough the fixed contacts are spaced from each other as shown in theswitch according to FIG. 3.

FIG. 6 finally illustrates a switch similar to those previouslydescribed in which, however, the rubber rod 22 according to FIGS. 1 and2 or the leaf spring 40 according to FIG. 3 is replaced by a torsioncoil spring 55 of spring steel provided with a loop 56 in the commonswing plane of lever 6 and tongue 18. For electrically insulating thecontrol lever 6 as well as this torsion spring 55 relative to thecontrol spring 18, the latter is provided with a part 57 which consistsof an electrically insulating material such as, for example, a plastic.This part 57 comprises a short tube 58 which projects through a bore 59in the control spring 18. Thanks to the provision of this insulatingpart 57, the fixed stop member 39 may consist of any desired materialjust like the stop member 39 according to FIG. 1.

Although out invention has been illustrated and described with referenceto the preferred embodiments thereof, we wish to have it understood thatit is in no way limited to the details of such embodiments but iscapable of numerous modifications within the scope of the appendedclaims.

Having thus fully disclosed our invention, we claim:

1. A snap switch comprising:

contact means including a mobile leaf spring movable between a first anda second position;

a swingable tongue adjacent said leaf spring;

a toggle spring interconnecting said tongue and said leaf spring fortranslating a swing of the former past a dead center position into anopposite movement of the latter between said first and second positionsthereof;

a lever generally parallel to and spaced from said tongue swingablebetween an unoperated and an operated positlon;

an elongate resilient link with one end fixed to said lever and anotherend fixed to said tongue, said link extending generally tranverselybetween said lever and said tongue while allowing limited relativemotion thereof;

and actuating means for swinging said lever between said unoperated andoperated positions thereof with elastic deformation of said link for thestorage therein and sub- 3. A snap switch as defined in claim 2 whereinsaid lever has a pivoted end fulcrumed on said housing and a free endprovided with adjustable biasing means opposing a swing of said leverinto said operative position by the pressure of said fluid, said linkbeing fixed to said lever at a point intermediate said pivoted and freeends.

4. A snap switch as defined in claim 3 wherein said leaf spring and saidtongue are clamped to said housing on the side of said free end withreference to said link.

5. A snap switch as defined in claim 1 wherein said link is a rod ofelastomeric material.

6. A snap switch as defined in claim 5 wherein said rod has grooved endsfitted into holes of said lever and said tongue.

7. A snap switch as defined in claim 1 wherein said link is a bentspring.

8. A snap switch as defined in claim 7 wherein said bent spring isgenerally L-shaped with a first arm substantially parallel to said leverand with a second arm substantially perpendicular thereto, said firstarm and said lever being closely juxtaposed and provided with alignedapertures traversed by a part of said actuating means.

9. A snap switch as defined in claim 7, further comprising restainingmeans on said lever engaging said bent spring with play for limiting theelastic deformation thereof upon a swinging of said lever between saidunoperated and operated positions.

10. A snap switch as defined in claim 7 wherein said bent spring iscoiled into a loop substantially midway between said lever and saidtongue.

11. A snap switch as defined in claim 10 wherein said loop lies in thecommon swing plane of said lever and said tongue.

12. A snap switch as defined in claim 7 wherein said bent spring is ablade with a bifurcate end having prongs clamping said tongue betweenthem.

13. A snap switch as defined in claim 12 wherein said leaf spring islonger than said tongue and is longitudinally slotted for giving passageto said tongue upon a swinging thereof past dead center.

1. A snap switch comprising: contact means including a mobile leafspring movable between a first and a second position; a swingable tongueadjacent said leaf spring; a toggle spring interconnecting said tongueand said leaf spring for translating a swing of the former past a deadcenter position into an opposite movement of the latter between saidfirst and second positions thereof; a lever generally parallel to andspaced from said tongue swingable between an unoperated and an operatedposition; an elongate resilient link with one end fixed to said leverand another end fixed to said tongue, said link extending generallytranversely between said lever and said tongue while allowing limitedrelative motion thereof; and actuating means for swinging said leverbetween said unoperated and operated positions thereof with elasticdeformation of said link for the storage therein and subsequent releaseof a mechanical forCe swinging said tongue past said dead centerposition to control the position of said leaf spring.
 2. A snap switchas defined in claim 1, further comprising a housing supporting saidcontact means, said tongue and said lever, said actuating meansincluding a diaphragm substantially parallel to said lever andmechanically coupled therewith, said diaphragm forming part of a fluidchamber in said housing provided with inlet means for the admission of apressure fluid to displace said lever.
 3. A snap switch as defined inclaim 2 wherein said lever has a pivoted end fulcrumed on said housingand a free end provided with adjustable biasing means opposing a swingof said lever into said operative position by the pressure of saidfluid, said link being fixed to said lever at a point intermediate saidpivoted and free ends.
 4. A snap switch as defined in claim 3 whereinsaid leaf spring and said tongue are clamped to said housing on the sideof said free end with reference to said link.
 5. A snap switch asdefined in claim 1 wherein said link is a rod of elastomeric material.6. A snap switch as defined in claim 5 wherein said rod has grooved endsfitted into holes of said lever and said tongue.
 7. A snap switch asdefined in claim 1 wherein said link is a bent spring.
 8. A snap switchas defined in claim 7 wherein said bent spring is generally L-shapedwith a first arm substantially parallel to said lever and with a secondarm substantially perpendicular thereto, said first arm and said leverbeing closely juxtaposed and provided with aligned apertures traversedby a part of said actuating means.
 9. A snap switch as defined in claim7, further comprising restaining means on said lever engaging said bentspring with play for limiting the elastic deformation thereof upon aswinging of said lever between said unoperated and operated positions.10. A snap switch as defined in claim 7 wherein said bent spring iscoiled into a loop substantially midway between said lever and saidtongue.
 11. A snap switch as defined in claim 10 wherein said loop liesin the common swing plane of said lever and said tongue.
 12. A snapswitch as defined in claim 7 wherein said bent spring is a blade with abifurcate end having prongs clamping said tongue between them.
 13. Asnap switch as defined in claim 12 wherein said leaf spring is longerthan said tongue and is longitudinally slotted for giving passage tosaid tongue upon a swinging thereof past dead center.